1. Field of the Invention
The present invention relates to an engine exhaust heat temperature detection device for performing temperature detection of heat exhausted from an engine.
2. Description of Related Art
As an engine exhaust heat temperature detection device detecting a temperature of heat exhausted from an engine, conventional examples are known that are provided with structures disclosed in the following [1] and [2].
[1] An exhaust gas purification device that also serves as a muffler is provided on an upper rear side of an engine, and a detection portion of an exhaust gas temperature sensor is inserted into the inside of the exhaust gas purification device to detect the temperature of an exhaust gas that exists inside the exhaust gas purification device (see Related Art 1).
[2] A muffler is provided in the middle of an exhaust gas emission passage of an engine, and in addition, a temperature sensor for detecting an exit temperature of the exhaust gas is provided at an outlet of the muffler to detect the temperature of the exhaust gas at the outlet of the muffler (see Related Art 2).
[Related Art 1] Japanese Patent Laid-Open Publication No. 2011-47773 (paragraph [0038], FIGS. 1 and 4).
[Related Art 2] Japanese Patent Laid-Open Publication No. HEI 6-249010 (paragraph [0008], FIG. 1).
In the structure disclosed in Related Art 1, the temperature of the exhaust gas inside the exhaust gas purification device that also serves as a muffler is detected; and in the structure disclosed in Related Art 2, the temperature of the exhaust gas at the outlet of the muffler is detected. In these structures, the temperature of the exhaust gas is directly detected by using an exhaust gas temperature detection sensor. Therefore, as the exhaust gas temperature detection sensor, it is necessary to use a sensor for high temperature detection that has superior heat resistance so as to be capable of performing temperature detection while being exposed to a high temperature exhaust gas. For this reason, the exhaust gas temperature detection sensor itself becomes expensive, which tends to lead to an increase in the cost of the exhaust gas temperature detection device of the engine.